Nitrogen in Flowers Soraya Ruamrungsri, Kanokwan Panjama, Takuji Ohyama and Chaiartid Inkham
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Chapter Nitrogen in Flowers Soraya Ruamrungsri, Kanokwan Panjama, Takuji Ohyama and Chaiartid Inkham Abstract This chapter explores the literature and research on nitrogen in flowers. An overview of nitrogen deficiency symptoms in some flowers, i.e., Curcuma alismati- folia (ornamental curcuma), Tagetes erecta (marigold), Zinnia violacea (zinnia), and Gomphrena globose (gomphrena) were presented. Additionally, nitrogen uptake, translocation, and application in some flowers, i.e., ornamental curcuma, narcis- sus, orchids, and rose, were discussed in this chapter. Nitrogen affects the life cycle of flower, including vegetative and reproductive phases. Flower size, stem length, number of flowers per plant, and color were reduced by nitrogen deficiency. Therefore, the optimum level of nitrogen supply in each growth stage is important for flower crop production. Keywords: nitrogen deficiency, nitrogen uptake, nitrogen application, nitrogen translocation, flowers 1. Introduction Flower crops, similar to other horticultural crops, require optimum fertilizer for a good quality flower size, stem length, number of florets, stem, and petal color. Essential elements, especially nitrogen, play an important role in growth and development in each stage of the life cycle. Different genera have different nitrogen requirements. Generally, they have a nitrogen content that is enough for root emergence and shoot sprouting. However, flowers grown from seeds may require fertilizer as soon as root emergence. A lack of fertilizer supply will lead to severe nutrient deficiency. Seed germination starts with water uptake, and then food reserves, i.e., carbohydrates and storage proteins, are oxidized for the growth process [1]. Flower seedlings show deficiency symptoms when the fertilizer supply is not enough. Nitrogen is an especially important element in the life cycle of plants from seedlings to the vegetative stage and flowering until senescence. It affects flower qualities, such as size, stem length, and color. This chapter focuses on the role of nitrogen in some economic flower crops. Most information was derived from our research experiments and some are unpublished data. 2. Nitrogen deficiency symptoms in different flower species 2.1 Curcuma alismatifolia (ornamental curcuma) Nitrogen deficiency (-N) affected the growth and characteristics of C. alismatifolia (Table 1 and Figure 1). Most growth parameters, such as plant 1 Nitrogen in Agriculture - Physiological, Agricultural and Ecological Aspects Nutrient Plant growth at flowering stage (12 weeks after planting) solution Plant No. Root Leaf green color Leaf Total Total Height leaves length intensity (SPAD area fresh dry (cm) per (cm) unit) (cm2) weight weight plant (g) (g) Old Yo u n g leaf Leaf Complete 49.1 a 5.0 a 42.8 a 5 7.1 a 52.5 a 253.8 a 285.0 a 31.3 a -N 36.0 b 4.3 a 40.6 b 34.2 b 52.8 a 191.2 b 111.4 b 14.7 b %CV 8.7 8.8 0.9 10.8 4.9 10.6 11.0 12.4 LSD 0.05 * NS * * NS * * * *Means within the same column followed by different letters were significantly different in an LSD test; (p ≤ 0.05). NS = not significant. Table 1. Plant growth of Curcuma alismatifolia treated with complete nutrient solution or nitrogen deficiency (-N) at the flowering stage (12 weeks after planting). Figure 1. Growth and flower quality of Curcuma alismatifolia was affected by complete nutrient solution (control) and nitrogen deficiency (-N) treatment at the flowering stage (12 weeks after planting). (photo by Chaiartid Inkham). height, root length, leaf area, and total fresh and dry weight, were higher when plants were supplied with a complete nutrient solution, rather than -N treatment (Table 1). However, there was no significant difference in the number of leaves per plant between plants supplied with complete nutrient solution and -N treat- ment (Table 1). The characterization of nitrogen deficiency symptoms in C. alis- matiflolia were evaluated at the flowering stage (12 weeks after planting). Leaves are the main plant part in which visual symptoms of the plant’s response to nitrogen deficiency are usually observed. When there is a nitrogen deficit, older leaves of C. alismatifolia turn yellow and brown, while young leaves still appear green (Figure 1). The old leaves’ green color intensity in -N treatment was lower than those treated with the complete nutrient solution (34.2 and 57.1 SPAD unit, 2 Nitrogen in Flowers DOI: http://dx.doi.org/10.5772/intechopen.98273 respectively). There was no significant difference among treatments in young leaves (Table 1). This result could explain nutrient remobilization processes in plants. Nitrogen is a macronutrient that is highly mobile in the phloem [2]; therefore, in N deficit conditions, nitrogen in old leaves of C. alismatifolia may be remobilized and translocate to young leaves. The remobilization of nutrients is frequently associated with foliar senescence, which makes nutrients available for younger plant organs and contributes to nutrient use efficiency [3]. Nitrogen deficiency delays flowering in C. alismatifolia and decreased flower quality in term of inflorescent length. However, there were no significant differ- ences in inflorescence width, stalk length, and number of inflorescences per plant (Table 2 and Figure 1). Nitrogen deficiency delayed flowering in narrow-leafed lupin [4]. The production of C. alismatifolia, in terms of flower quality and rhizome yield, depends on the response to N fertilizers [5]. Nitrogen-deficient plants are stunted and the quality of their flowers and rhizomes is significantly decreased. The increase of nitrogen from 0 to 50 mg L−1 increased the number of flowering shoots and, consequently, the number of rhizomes [6]. 2.2 Tagetes erecta L. (Marigold) The overall growth parameters of marigold were decreased under nitrogen deficit conditions (Table 1 and Figure 2). At 8 weeks after planting, plants in the -N treatment were stunted with a plant height of only 47.5 cm, which was 42.2 cm shorter than plants in the complete nutrient solution treatment. Moreover, there was a dramatic decrease in leaf area and the total fresh weight of marigolds grown under -N treatment when compared with complete nutrient solution treatment (decreasing 82 and 90%, respectively) (Table 3). Leaf green color intensity of marigold was detected both in young leaves and old leaves to evaluate visual symptoms of plants grown under -N conditions. The results showed that leaf green color intensity of marigold in both young and older leaves was lower when grown under -N treatment than grown under complete nutrient solution treatment (Table 3). In addition, the leaves of plants under -N treatment were smaller than those under complete nutrient solution treatment. Older leaves turned yellow, red and brown, while young leaves had symptoms of chlorosis and turned light yellow (Figure 2). Plant height, plant spread, and the number of primary branches per plant of African marigold increased significantly with the increase in nitrogen level from 0 to 30 g m−2 [7]. A suitable supply of N enhanced plant growth effi- ciency, thus increasing plant yield and flower quality [8]. Nutrient Flower quality solution Days to Inflorescence Inflorescence Stalk No. flowering width (cm) length (cm) length inflorescence (day) (cm) per plant Complete 70.7 b 6.9 a 11.8 a 34.3 a 1.0 a -N 78.3 a 5.8 a 9.9 b 29.4 a 1.0 a %CV 0.8 9.7 4.7 8.1 0 LSD 0.05 * NS * NS NS *Means within the same column followed by different letters were significantly different in an LSD test; (p ≤ 0.05). NS = not significant. Table 2. Flower quality of Curcuma alismatifolia treated with complete nutrient solution or nitrogen deficiency (-N) at the flowering stage (12 weeks after planting). 3 Nitrogen in Agriculture - Physiological, Agricultural and Ecological Aspects Figure 2. Growth and flower quality of marigold was affected by complete nutrient solution (control) and nitrogen deficiency (-N) treatments at the flowering stage (8 weeks after planting). (photo by Chaiartid Inkham). Nutrient Plant growth at flowering stage (8 weeks after planting) solution Plant Root Leaf green color Leaf area Total fresh Height length intensity (SPAD unit) (cm2) weight (g) (cm) (cm) Old Young Leaf leaf Complete 89.7 a 28.3 b 43.9 a 45.5 a 3,990.3 a 889.8 a -N 47.5 b 36.5 a 23.2 b 22.2 b 706.3 b 88.7 b %CV 8.9 5.9 14.1 19.0 40.3 2.7 LSD 0.05 * * * * * * *Means within the same column followed by different letters were significantly different in an LSD test; (p ≤ 0.05). Table 3. Plant growth of marigold treated with complete nutrient solution or nitrogen deficiency (-N) at the flowering stage (8 weeks after planting). Flowering of marigold was delayed under nitrogen deficiency condition (about 12 days delay when compared with complete nutrient treatment) (Table 4). Furthermore, the flower quality in terms of flower width, flower length, and stalk length were also reduced in plants in the -N treatment compared to those treated with the complete nutrient solution (Table 4, Figure 2). The flower yield of mari- gold was highly sensitive to nitrogen deficiency, since there was a 90% decrease in the number of flowers per plant when the plants were grown under -N treatment compared with the complete nutrient solution treatment (Table 4). In marigold (Calendula officinalis L. ‘TOKAJ’), nitrogen fertilization had a significant impact on the number of flower heads per plant (especially on the second-rank branches) [9]. 2.3 Zinnia violacea Cav. (zinnia) Nitrogen deficiency caused a decrease in plant height, number of leaves per plant, and root length of zinnia at 9 weeks after planting (Table 5). Additionally, yields of zinnia in terms of leaves area, total fresh weight, and total dry weight 4 Nitrogen in Flowers DOI: http://dx.doi.org/10.5772/intechopen.98273 Nutrient Flower quality solution Days to Flower Flower Stalk No.